Got a "new" volvo and I am very disappointed

[capnjim]

Thanks, where exactly are these rings and bolts? At least its something to check to get started. I have also read the differential pump can cause this problem as well.

[capnjim]

Thanks, where are the rings and bolts? I can check this weekend. I also found a kit for 30$ on eBay to rebuild the Haldex pump which would be a cheap start.
Cheers!

[RickHaleParker]

But...the 4 wheel drive works intermittently.
I am hoping its not a tough fix.

It could be as simple as a dirty Differential Electronic Module (DEM) connector. Get back there at the rear end and clean electrical connectors. Same goes for any other system where you are having problems.

[- Pete -]

The ring VTL was talking about is on the outer CV joint on your CV axles. It spins just inside the knuckle & the hall sensor that is supposed to pick up its rate of spin is directly above it, protruding through the top of the knuckle, it’s a wheel speed sensor, basically.

You don’t even need to take your wheel off to see if the center bolt is present, loose, or otherwise. Just take out the center cap on your front/rear wheels & see if there’s a bolt there, then check for tightness. If tight, look for the next culprit. We’re it me & all 4 bolts were in place & tight, I’d start reading up on ABS module failures & Xemodex. Hopefully yours isn’t failed.

Onto the AWD, the sporadic nature of your functioning seems strange to me. Comforting in that it’s very likely your bevel gear (transfer case) is still ok & you’re facing an electrical malfunction. I don’t have a cursory knowledge of the AWD system but I have replaced a couple DEM pumps & several filters. DEM = Differential Electronic Module, often also called Haldex or AOC (Active On-demand Coupler). It lives at the front of the rear differential housing & is just aft of where your rear driveshaft mates up. The connectors on these can really be aggravating.

Do your best to not break them!

I’ve had it several times where I wasn’t able to get the connectors plugged back in all the way. In all these cases it was tiny stones resting up there in the valley between the two receptacle preventing them from being plugged in all the way. Blow out the area well with compressed air.

There was an update to the filter design on Haldex 3 systems. Here are some pics to help you get zero’d in on where it is. A wet Haldex unit is not a good thing. The wet pics are a customers car I took a quick peek at. You can see the “finned” cover on the bottom two pictures, that is the updated filter. Also circled in yellow & next to the filter is the DEM pump, black cylindrical object.

[capnjim]

Hey..thanks for that great detailed reply. From my research, I am pretty sure its the pump as well.
eBay actually sells a kit to rebuild them for 30$. That's a cheap place to start.
Unfortunately, its way too cold out now for me to be crawling around under the car in my driveway.
I'll get through the winter and fix it up in the spring/summer and have it all worked out for next winter.
Cheers

[pbierre]

The common element in your ABS and AWD systems is the Hall Effect wheel sensors. If you can hook up to VIDA, you'll get detailed info. If a wheel sensor is bad, it'll say which wheel.

Please stop referring to AWD as "4 wheel drive". The latter implies a hard mechanical linkage of torque to all 4 wheels.
The AWD on Volvos is a FWD, augmented with on demand, smart-clutch-linked rear-wheel torque of between 10% and 50%.
The concept is that torque is delivered to the rear wheels when the front wheels are losing traction (slipping). How is this determined?

Each wheel has its own axle speed sensor (a Hall Effect sensor that receives blips from a toothed wheel on the axle). Front-wheel loss of traction is inferred when the fronts are spinning faster than the rears. The AWD computer responds by sending more torque to the rear wheels until the front-rear wheels come back into sync. Thus the term "on-demand" given to the job of the Haldex smart clutch where the variable torque transmission takes place.

The baseline torque to the rear wheels is about 10% (front and rear wheels turning at approx. same speed). During front wheel slippage, the rears max out at 50% torque, emulating the power split in a 4WD. But this only lasts long enough to end front wheel slippage.

From this AWD design, you can see how dependent it is on the wheel speed sensors.

[capnjim]

Thanks, so chances are its a bad wheel speed sensor? They are not very expensive. Maybe I should just change all 4 of them??

https://www.rockauto.com/en/moreinfo.ph ... 3&jsn=1521

[capnjim]

Also, I had the front shocks changed and rear bearings changed. Maybe they got damaged then. Amazon has them for under 50$

[vtl]

Please stop referring to AWD as "4 wheel drive". The latter implies a hard mechanical linkage of torque to all 4 wheels.

4WD may have differentials. In that respect Haldex is a differential.

My Tundra has part-time 4WD with open rear diff. No other diffs. It is unusable on paved roads, making Volvo AWD way more agile and safer.

The AWD on Volvos is a FWD, augmented with on demand, smart-clutch-linked rear-wheel torque of between 10% and 50%.
The concept is that torque is delivered to the rear wheels when the front wheels are losing traction (slipping).

This was true for viscous coupler. Haldex proactively determines what car is doing and adds power to the rear before the front axle looses traction. It still may get the front wheels spinning when DEM mispredicts, but generally any time you accelerate or even turn steering wheel the Haldex engages more.

[xHeart]

I spent 5k on it. the engine is awesome. Stereo is great, heater is great, I just want the 4x4 to work and i will keep if for as long as I can,.
Cheers from Canada!!!

Here is your checklist to get the great looking 2006 XC70 under your ownership. https://www.volvoxc.com/wp-content/uplo ... cklist.pdf.